PEARL HARBOR OPERATIONS:

General Outline of Orders and Plans

Prepared by
Military History Section
Headquarters, Army Forces Far East

Distributed by
Office of the Chief of Military History
Department of the Army

[Page ii blank]

[Page iii]

FOREWORD

This monograph is a collection of pertinent Navy Orders and Directives, Combined Fleet Orders, and Carrier Striking Task Force Orders concerning the Pearl Harbor operation. Since all copies of these orders were destroyed prior to the end of the war, they have been reconstructed from personal notes and memory.

In editing, explanatory footnotes were added when deemed necessary.

19 February 1953

[Page iv blank]

[Page v]

Preface

Through Instructions No. 126 to the Japanese Government, 12 October 1945, subject: Institution for War Records Investigation, steps were initiated to exploit military historical records and official reports of the Japanese War Ministry and Japanese General Staff, and the transfer of their former functions to the Demobilization Bureau, research and compilation continued and developed into a series of historical monographs.

The paucity of original orders, plans and unit journals, which are normally essential in the preparation of this type of record, most of which were lost or destroyed during field operations or bombing raids rendered the task of compilation most difficult; particularly distressing has been the complete lack of official strength reports, normal in AG or G3 records. However, while many of the important orders, plans and estimates have been reconstructed form memory and therefore are not textually identical with the originals, they are believed to be generally accurate and reliable.

Under the supervision of the Demobilization Bureau, the basic material contained in this monograph was compiled and written in Japanese by former officers, on duty in command and staff units within major units curing the period of operations. Translation was effected through the facilities of Military Intelligence Group, G2, Headquarters, Far East Command.

[Page vi]

This Japanese Operational Monograph was rewritten in English by the Japanese Research Division, Military History Section, Headquarters, Army Forces Far East and is based on the translation of the Japanese original. Editorial corrections are limited to those necessary for coherence and accuracy.

1. In view of the great possibility of being compelled to go to war against the United States, Great Britain and the Netherlands in the cause of self-existence and self-defense, Japan has decided to complete various operational preparations within the first ten days of December.

2. The Commander-in-Chief of the Combined Fleet will make the necessary operational preparations.

3. The details of the operation shall be directed by the Chief of the Naval General Staff.

By Imperial OrderChief of the Naval General StaffNagano, Osami

Navy Directive No. 1

5 November 1941Directive to: Yamamoto, C in C, Combined Fleet

1. The Combined Fleet will advance necessary forces at a suitable time to their preparatory points to stand by for the start of operations in the event of unavoidable hostilities against America,

[Page 2]

Great Britain and the Netherlands, in the first ten days of December. [1]

2. During the above-mentioned advance, strict watch will be kept against unexpected attacks.

3. The operational policy against America, Great Britain, and the Netherlands, in case of hostilities, is scheduled as cited in the separate volume. [2]

Chief of the Naval General StaffNagano, Osami

Note:

Combined Fleet Operations Order No. 1 issued on 5 November 1941 and titled "Preparations for War and Commencement of Hostilities" was an 89-page volume covering all phases of war preparations. In general this order stated the following:

a. The Empire is expecting war to break out with the United States, Great Britain and the Netherlands. When the decision is made to complete all operational preparations, orders will be issued es-

tablishing the approximate date (Y Day) for commencement of hostilities and announcing "First Preparations for War."

When these orders are issued, the forces will act as follows:

(1) All fleets and forces, without special orders, will organize and complete battle preparations for operations in accordance with "the Allocation of Forces for First Period Operations of First Phase Operations." When directed by respective commanding officers, they will proceed at a proper time to the pre-operation rendezvous points and wait in readiness.

(2) All forces will be on strict look-out for unexpected attacks by the U.S., British, and Netherlands forces.

(3) The commanding officers of various forces may carry out such secret reconnaissance as is necessary for the operations.

[Page 4]

Combined Fleet Operations Order No. 2

7 November 1941Order to: Combined Fleet

First Preparations for WarY Day 8 December. [3]

C in C, Combined FleetYamamoto, Isoroku

[3]. This order was issued by C in C, Combined Fleet, after he had
received verbal notification from Chief, Naval General Staff, that 8
December had been tentatively selected as "Y" Day.

[Page 5]

Navy Order No. 5

21 November 1941Order to: Yamamoto, C in C, Combined Fleet

1. The Commander-in-Chief of the Combined Fleet will dispatch at an appropriate time the necessary forces for the execution of operations to positions of readiness. [4]

2. The Commander-in-Chief of the Combined Fleet is empowered to use force in self-defense in case his fleet is challenged by American, British or Dutch forces during the process of carrying out military preparations.

3. The details concerned will be directed by the Chief of the Naval General Staff. [5]

By Imperial OrderChief of the Naval General StaffNagano Osami

[4]. So-called positions of readiness were designated operational sea
areas. They were as follows:
Southern Force (2nd, 3rd and South China Sea
Southern Expeditionary Fleets) (Elements in Western
Caroline Area)
South Seas Force (4th Fleet) Inner South Seas Area
Northern Force (5th Fleet) Kurile Area
Submarine Force (6th Fleet) Hawaiian Sea Area
Carrier Striking Task Force Hawaiian Sea Area
(1st Air Fleet)
Commerce Destruction Force Indian Ocean
Land Based Air Force (11th Air Fleet) Formosa, French Indo-
China and Palau
[5]. On the same day C in C, Combined Fleet, issued the necessary orders
for dispatch of forces to the designated operational sea areas. Time of
departure was left to the discretion of respective force commanders.

[Page 6]

Navy Directive No. 5

21 November 1941Directive to: Yamamoto, C in C, Combined Fleet

1. The Commander-in-Chief of the Combined Fleet will immediately assemble and call back the operational units if the Japanese-American negotiation is successful.

2. The exercise of military authority cited in the Imperial General Headquarters Navy Order No. 5 will be effected in the event the American, British, or Dutch naval forces invade our territorial waters and carry out reconnaissance, or approach our territorial waters and their move is recognized to be threatening, or an aggressive act is taken to endanger us even beyond our territorial waters.

Chief of the Naval General StaffNagano, Osami

[Page 7]

Carrier Striking Task Force Operations Order No. 1 [6]

23 November 1941To: Carrier Striking Task Force

1. The Carrier Striking Task Force will proceed to the Hawaiian Area with utmost secrecy and, at the outbreak of the war, will launch a resolute surprise attack on and deal a fatal blow to the enemy fleet in the Hawaiian Area. The initial air attack is scheduled at 0330 hours, X Day. Upon completion of the air attacks, the Task Force will immediately withdraw and return to Japan and, after taking on new supplies, take its position for Second Period Operations. In the event that, during this operation, an enemy fleet attempts to intercept our force or a powerful enemy force is encountered and there is danger of attack, the Task Force will launch a counterattack.

2. The disposition of Force will be as shown on Chart 1.

3. The Operation of Each Force.

a. General

While exercising strict antiaircraft and antisubmarine measures and making every effort to conceal its position and movements, the entire force (except the Midway Bombardment Unit) in accordance with special orders will depart as a group from Hitokappu Bay at a speed of 12-14 knots. The force refueling en route whenever possible will arrive at the standby point (42 N, 165 W). In the event bad weather prevents refueling en route to the standby point, the screening unit will be

ordered to return to the home base. Subsequent to the issuance of the order designating X Day (the day of the outbreak of hostilities), the force will proceed to the approaching point (32 N, 157 W).

[Page 11]

Around 0700 hours, X-1 Day the Task Force will turn southward at high speed (approximately 24 knots) from the vicinity of the approaching point. It will arrive at the take-off point (200 nautical miles north of the enemy fleet anchorage) at 0100 hours X Day (0530 Honolulu time) and commit the entire air strength to attack the enemy fleet and important airfields on Oahu.

Upon completion of the air attacks, the Task Force will assemble the aircraft, skirt 800 nautical miles north of Midway, return about X + 15 Day to the western part of the Inland Sea via the assembly point (30 N, 165 E) and prepare for Second Period Operations. In the event of a fuel shortage the Task Force will proceed to Truk via the assembly point.

The force may skirt near Midway in the event that consideration of an enemy counter-attack is unnecessary due to successful air attacks or if such action is necessitated by fuel shortage.

In this event, the 5th Carrier Division with the support of the Kirishima from the 3rd Battleship Division will leave the Task Force on the night of X Day or the early morning of X + 1 Day and carry out air attacks on Midway in the early morning of X + 2 Day.

If a powerful enemy force intercepts our return route, the Task Force will break through the Hawaiian Islands area southward and proceed to the Marshall Islands.

b. Patrol unit

The patrol unit will accompany the main force. In the event the screening unit is returned to the home base, the patrol unit

[Page 12]

will screen the advance of the main force and the launching and the landing of aircraft. After the air attacks, the patrol unit will station itself between the flank of the main force and the enemy. In the event of an enemy fleet sortie, the patrol unit will shadow the enemy and in a favorable situation attack him.

c. The Midway Bombardment Unit

The Midway Bombardment Unit will depart from Tokyo Bay around X-6 Day and, after refueling, secretly approach Midway. It will arrive on the night of X Day and shell the air base. The unit will then withdraw and, after refueling, return to the western part of the Inland Sea. The oiler Shiriya will accompany the bombardment unit on this mission and will be responsible for the refueling operation.

d. Supply Force

The supply force will accompany the main force to the approaching point, carrying out refuelings, separate from the main force, skirt 800 nautical miles north of Midway, return to the assembly point by 0800 hours, X +6 Day, and stand by.

4. The Task Force may suspend operations en route to the Hawaiian area and return to Hitokappu Bay, Hokkaido or Mutsu Bay, depending upon the situation.

CommanderCarrier Striking Task ForceNagumo, Chuichi

[Page 13]

Carrier Striking Task Force Operations Order No. 3 [7]

23 November 1941To: Carrier Striking Task Force

The Hawaiian operations air attack plan has been decided as follows:

1. The Operation of the Air Attack Forces

The force will be 700 nautical miles due north of point Z (set at the western extremity of the Island of Lanai) at 0600 hours X-1 Day and advance on a course of 180 degrees from 0700 hours X-1 Day at an increased speed of 24 knots.

Air attacks will be carried out by launching the first attack units 230 nautical miles due north of Z point at 0130 hours X Day, and the second attack unit at 200 nautical miles due north of Z point at 0245 hours.

After the launching of the second attack units is completed, the task force will withdraw northward at a speed of about 24 knots. The first attack units are scheduled to return between 0530 and 0600 hours and the second attack units are scheduled to return between 0645 and 0715 hours.

Immediately after the return of the first and second attack units, preparations for the next attack will be completed. At this time, carrier attack planes capable of carrying torpedoes will be armed with such as long as the supply lasts.

[7]. General outline.

[Page 14]

If the destruction of enemy land-based air strength progresses favorably, repeated attacks will be made immediately and thus decisive results will be achieved.

In the event that a powerful enemy surface fleet appears, it will be attacked.

2. Organization of the Air Attack Units

(see Chart 2)

3. Targets

a. The First Attack Units

The targets for the first group will be limited to about four battleships and four aircraft carriers; the order of targets will be battleships and then aircraft carriers.

The second group will attack the enemy land-based air strength according to the following assignment:

The 15 Attack Unit: Hangars and aircraft on Ford Island

The 16 Attack Unit: Hangars and aircraft on Wheeler Field

The targets of Fighter Combat Units will be enemy aircraft in the air and on the ground.

b. The Second Attack Units

The first group will attack the enemy air bases according to the following assignment:

or five enemy aircraft carriers. If the number of targets is insufficient, they will select targets in the order of cruisers and battleships.

The Fighter Combat Units will attack the enemy aircraft in the air and on the ground.

4. Attack Procedure

a. The First Attack Units

(1) With the element of surprise as the principle, attacks will be carried out by the torpedo unit and bomber unit of the First Group, and then the Second Group.

(2) During the initial phase of the attack, the Fighter Combat Units will, in one formation, storm the enemy skies about the same time as the First Group, and contact and destroy chiefly the enemy interceptor planes.

In the event that no enemy aircraft are encountered in the air, the units will immediately shift to the strafing of parked aircraft as follows:

1st and 2nd Fighter Combat Units: Ford Island and Hickam Field.

3rd and 4th Fighter Combat Units: Wheeler Field and Barbers Point.

5th and 6th Fighter Combat Units: Kaneohe

(3) In the event that the advantage of surprise attack cannot be expected due to strict enemy security, the

[Page 18]

approach and attack will be made in the order of the Fighter Combat Units, Dive Bombing Units, Horizontal Bombing Units and the Torpedo Attacking Units.

b. The Second Attack Units

All units will storm the enemy skies almost simultaneously and launch the attacks.

Although the general outline of the operations of the Fighter Combat Units corresponds to that of the First Attack Units, the strafing will be carried out according to the following in case there are no enemy aircraft in the air.

1st and 2nd Fighter Combat Units: Ford Island and Hickam Field

3rd and 4th Fighter Combat Units: Wheeler Field and Kaneohe

c. The general outline of attack in the event that enemy aircraft carriers and the main body of the U.S. Fleet are in anchorages outside Pearl Harbor are:

(1) The organization and targets are the same as mentioned above. The First Attack Units of the First Group, however, will increase the number of torpedo bombers as much as possible.

(2) Escorted by the Fighter Combat Units, the Air Attack Units will proceed in a group and attack the designated targets in the order of the enemy fleet anchorages and the Island of Oahu. If attacks on

[Page 19]

the enemy fleet anchorages progress favorably, however, the Fighter Combat Units and the 2nd Group of the First Air Attack Unit will immediately proceed to the Island of Oahu. Upon completion of the attacks, the anchorage attack unit will return directly to the carriers.

d. Rendezvous for Return to Carriers

(1) The rendezvous point will be 20 nautical miles at 340 degrees from the western extremity (Kaena Point) of the Island of Oahu. The rendezvous altitude will be 1,000 meters. (If this vicinity is covered with clouds, it will be below the cloud ceiling.)

(2) The Attack Units will wait at the rendezvous point for about 30 minutes and return to their carriers, after being joined by the Fighter Combat Units.

(3) While returning to carriers, the Fighter Combat Unit will become the rear guards for the whole unit and intercept any enemy pursuit.

5. Reconnaissance

a. Pre-operation Reconnaissance

Pre-operation reconnaissance will not be carried out unless otherwise ordered.

[Page 20]

b. Immediate Pre-attack Reconnaissance

Two reconnaissance seaplanes of the 8th Cruiser Division will take off at 0030 hours, X Day, secretly reconnoiter Pearl Harbor and Lahaina Anchorage and report the presence of the enemy fleet (chiefly carriers and the main body of the fleet).

c. Scouting Patrol

The reconnaissance seaplanes of the 8th Cruiser Division will take off at 0300 hours and will carry out an extensive search of the waters between the enemy and the friendly forces and the waters adjacent to the two channels situated to the east and west of the Island of Oahu. They will observe and report the presence and activities of the enemy sortie force and enemy aircraft on counter-attack missions.

d. Before returning to its carrier, after the attack, an element of fighters designated by the Fighter Combat Unit Commander will fly as low and as fast as circumstances permit and observe and determine the extent of damage inflicted upon the enemy aircraft and ships.

Air Security Disposition No. 1 Method B will be followed from one hour before sunrise until 45 minutes after sunset on the day of the air attack. [8]

Commander

Carrier Striking Task Force

Nagumo, Chuichi

[8] This Security Disposition called for combat air cover over the
carriers.

[Page 21]

Combined Fleet, Operations Order No. 5 (General Outline)

25 November 1941Order to: Carrier Striking Task Force

The Carrier Striking Task Force will immediately complete taking on supplies and depart with utmost secrecy from Hitokappu Bay on 26 November and advance to the standby point (42 N, 170 W) by the evening of 3 December.

Commander-in-Chief, Combined Fleet

Yamamoto, Isoroku

[Page 22]

Navy Order No. 9

1 December 1941Order to: Yamamoto, C in C, Combined Fleet

1. Japan has decided to open hostilities against the United States, Great Britain, and the Netherlands early in December.

2. The Commander-in-Chief of the Combined Fleet will smash the enemy fleets and air forces in the Orient and at the same time will intercept and annihilate enemy fleets should they come to attack us.

3. The Commander-in-Chief of the Combined fleet will occupy immediately the key bases of the United States, Great Britain, and the Netherlands in East Asia in close cooperation with the Commander-in-Chief of the Southern Army and will capture and secure the key areas of the southern regions.

4. The Commander-in-Chief of the Combined fleet will cooperate with the operations of the China Area Fleet, if necessary.

5. The time of the start of operations based on the aforementioned items will be made known later.

6. The Chief of the Naval General Staff will issue instructions concerning particulars.

By Imperial OrderChief of the Naval General StaffNagano, Osami

[Page 23]

Navy Directive No. 9

1 December 1941Directive to: Yamamoto, C in C, Combined Fleet

Operations of the Combined Fleet against American, England and Holland will be conducted in accordance with the Separate Volume, Imperial Navy's Course of Action in Operations against United States, Great Britain and the Netherlands.

Chief of the Naval General StaffNagano, Osami

[Page 24]

Navy Order No. 12

2 December 1941Order to: Yamamoto, C in C, Combined Fleet

1. As of 8 December the Commander-in-Chief of the Combined Fleet will start military operations in accordance with Imperial General Headquarters Navy Order No. 9.

2. Military operations will be launched against the Netherlands at an opportune time after attacking the United States and Great Britain.

Should it appear certain that Japanese-American negotiations will reach an amicable settlement prior to the commencement of hostilities, it is understood that all elements of the Combined Fleet are to be assembled and returned to their bases in accordance with separate orders.

Chief of the Naval General StaffNagano, Osami

Combined Fleet Telegraphic Operations Order No. 021730

(Date and time of dispatch)

8th December designated as X Day.

Commander-in-Chief, Combined FleetYamamoto, Isoroku

[Page 26 blank]

[Page 27]

APPENDIX I

Imperial Navy's Course of Action in Operations Against

United States, Great Britain, and the Netherlands

(Attached to Navy Directives No. 1 and No. 9)

I. Outline of Operations

Continue control over China Coast and Yangtze River.

Quickly destroy enemy fleet and air power in East Asia.

Occupy and hold strategic points in Southern Area.

Destroy enemy fleet.

Consolidate strength to hold out for a long time and destroy enemy's will to fight.

II. Combined Fleet Course of Action

(a) The First Phase of Operations

1. With the forces of the Second Fleet, Third Fleet, First Expeditionary Fleet and Eleventh Air Fleet as a nucleus destroy enemy fleets and air forces in the Philippines, British Malay, and Netherlands Indies. In cooperation with the Army, take the initiative in attacks on air forces and fleets in the Philippines and Malaya. Push forward our bases by landing advance troops. Then with main body of invasion forces occupy the Philippines and Malaya.

In early stages of operations, first occupy British Borneo and then as quickly as possible occupy Dutch Borneo, Celebes and Southern Sumatra. The above to be followed by occupation of Molucca Islands and Timor. Established air bases in all of

[Page 28]

the above-mentioned places. Utilize the air bases for subjugation of Java and then occupy Java. After capture of Singapore, occupy northern Sumatra and then at an opportune time commence operations in Burma. Cut supply routes to China.

2. Forces of the Fourth Fleet.

Patrol, maintain surface communications, and defend the South Sea Islands. Capture Wake. At opportune time attack and destroy enemy advance bases in the South Pacific Area. In cooperation with Army capture Guam and then at an opportune time Bismarck Area.

3. Forces of the Fifth Fleet.

Patrol the area east of the home islands. Make preparations against surprise attacks by enemy. Make reconnaissance of Aleutians and defend Bonin Islands. Maintain surface communications. Be on guard against Soviet Russia.

4. Forces of the Sixth Fleet. (Submarines)

Make reconnaissance of American Fleet in Hawaii and West Coast areas and, by surprise attacks on shipping, destroy lines of communications.

Destroy enemy lines of communication in the Pacific and Indian Oceans.

(b) Second Phase of Operations.

1. Forces of Sixth Fleet. (Submarines)

Make reconnaissance and surprise attacks on main forces of enemy fleet. Destroy enemy surface communications in cooperation with a part of Combined Fleet. At opportune time make surprise attacks on enemy advanced bases.

2. Forces of First and Eleventh Air Fleets. (Carriers and Land-Based Air Forces)

Search for and attack enemy forces. Destroy enemy advanced bases.

3. Forces of Third Fleet, First Expeditionary Fleet and Other Forces as Necessary.

Defend and patrol points in South Seas Islands and Bismarcks. Maintain surface communications. Search for and attack enemy shipping. Make surprise attacks and destroy enemy bases on our perimeter.

[Page 30]

5. Forces of Fifth Fleet

Defend Bonin Islands and patrol area to north of those islands and east of home islands. Maintain surface communications. Search for and attack enemy fleet should it appear in the area. Attack and destroy enemy bases in the Aleutians.

6. Part of Combined Fleet. (24th Commercial Destruction Unit)

Destroy enemy surface communications in Pacific and Indian Oceans.

7. Main Body of Combined Fleet.

Support all operations. Operate as required.

8. In case of attack by strong American Force.

A part of the Sixth Fleet will maintain contact with the enemy. Reduce enemy strength by air and submarine attacks. At suitable opportunity assemble major portion of Combined Fleet and destroy enemy.

9. In case of attack by strong British Force.

By movement the Third Fleet, Fourth Fleet, First Expeditionary Fleet, Air Force, and Submarine Squadrons will maintain contact with enemy force and destroy it by concerted attacks. The main body of Combined Fleet, depending upon the strength, movement and location of American Fleet, will also be used in destruction of the British Fleet.

10. The important places to be defended among the points which were to be occupied were as follows:

Continue operations against China. Cooperate with the Army in destruction of United States and British forces in China. Second China Fleet cooperate with Army in capture of Hong Kong and destruction of enemy forces there. Maintain surface communications along China coast. Prevent enemy from using China coast. Cooperate with Combined Fleet and Army in operations. (Escort of surface transport and defense of assembly points.)